package com.dan.util;

import java.security.Key;
import java.security.NoSuchAlgorithmException;
import java.security.SecureRandom;

import javax.crypto.Cipher;
import javax.crypto.KeyGenerator;

import sun.misc.BASE64Decoder;
import sun.misc.BASE64Encoder;

public class DESUtils {

	//1. 指定DES加密解密所用的密钥
	private static Key key;
	private static String KEY_STR = "John";
	
	static {
		try {
			KeyGenerator generator = KeyGenerator.getInstance("DES");
			generator.init(new SecureRandom(KEY_STR.getBytes()));
			key = generator.generateKey();
			generator = null;
		} catch (NoSuchAlgorithmException e) {
			throw new RuntimeException(e);
		}
	}
	
	//2. 对字符串进行DES加密，返回BASE64编码的加密字符串
	public static String getEncryptString(String str) {
		BASE64Encoder base64Encoder = new BASE64Encoder();
		try {
			byte[] strBytes = str.getBytes("UTF8");
			Cipher cipher = Cipher.getInstance("DES");
			cipher.init(Cipher.ENCRYPT_MODE, key);
			byte[] encryptStrBytes = cipher.doFinal(strBytes);
			return base64Encoder.encode(encryptStrBytes);
		} catch (Exception e) {
			throw new RuntimeException(e);
		}
	}
	
	//3. 对BASE64编码的加密字符串进行解密，返回解密后的字符串
	public static String getDecryptString(String str) {
		BASE64Decoder base64Decoder = new BASE64Decoder();
		try {
			byte[] strBytes = base64Decoder.decodeBuffer(str);
			Cipher cipher = Cipher.getInstance("DES");
			cipher.init(Cipher.DECRYPT_MODE, key);
			byte[] decryptStrBytes = cipher.doFinal(strBytes);
			return new String(decryptStrBytes, "UTF8");
		} catch (Exception e) {
			throw new RuntimeException(e);
		}
	}
	
	//4. 对入参的字符串进行加密，打印出加密后的串
	public static void main(String[] args) throws Exception {
		if(args == null || args.length < 1) {
			System.out.println("请输入要加密的字符， 用空格分隔。");
		}else {
			for (String arg : args) {
				System.out.println(arg + " : " + getEncryptString(arg));
			}
		}
	}
}
